yarn build shows deprication warnings

[adamcooper1386]

• NPM version (npm -v):
• Node version (node -v):
• Node Process (node -p process.versions):
• Node Platform (node -p process.platform):
• Node architecture (node -p process.arch):
• node-sass version (node -p "require('node-sass').info"):
• npm node-sass versions (npm ls node-sass):

Did a fresh install of node-sass using yarn and it seems like there are unhandled deprication warnings.

[nschonni]

Tracked in #2851